Printed circuit board connectors, such as elongated edge card connectors or SIMM sockets, typically use hold-down mechanisms such as mounting pegs or boardlocks to locate and retain the connector to the printed circuit board prior to or during processing. If the connector is not properly located and held to the board during handling and processing, the connector itself may become separated and damaged, or the fragile unsoldered leads may be damaged or incorrectly positioned. Furthermore, in surface mount applications, the surface mount leads can "float" off of the surface of the printed circuit board or miss the solder pads on the board entirely, resulting in open circuit conditions. Location and retention of the connector is particularly critical in applications where double-sided circuit boards are utilized and where the mounting pegs or boardlocks cannot protrude through the board where they may interfere with connectors or other circuit components.
Problems have been encountered in designing hold-down mechanisms with an optimization of the relative insertion forces and retention forces between the connector assembly and the printed circuit board. In other words, in designing mechanisms that provide adequate retention forces to hold the connector assembly to the printed circuit board, the insertion forces of the mechanism often are excessive. On the other hand, if the hold-down mechanism is designed with sufficient flexibility and resilience to lower the insertion forces, typically the retention forces of the mechanism are inadequate or at least compromised.
Furthermore, each connector user may have a different force requirement for a given connector configuration. That is, depending on the connector user's process for assembling or processing the connector, the insertion and retention force requirements may vary. For example, if a connector user is manually placing his connectors on a printed circuit board, he may want a low insertion force mounting peg design. He may have other requirements if the connector is being robotically placed or handled. If a second user has a secondary operation in his process that requires handling or shipment of a printed circuit board subsequent to mounting a connector, but prior to soldering it, a high retention force mounting peg may be required. Another user may require a lower retention force mounting peg where a higher retention force may place too much stress on the thinner substrate. Still further, in high density applications where terminals may be fragile, and in particular in surface mount applications, higher retention force mounting pegs may relieve solder joint stress and improve coplanarity of surface mount leads.
Heretofore, when a connector user's mounting peg insertion or retention force requirements varied, a new peg design was required, for example by increasing the diameter or the press-fit dimension of the peg with respect to a printed circuit board aperture. In a given connector, therefore, mold changeovers and design changes would be both expensive and laborious.
Therefore, there exists a need for an improved mounting peg construction which provides not only for optimization between low insertion forces and high retention forces in both through-hole and surface-mount applications, but for a peg construction which accommodates changing force requirements of a given connector in different applications. This invention is directed to satisfying that need and simplifying the previously laborious and expensive process of tool changeover due to the changing insertion and retention force requirements of a connector user by providing an improved hold-down mechanism construction and method for molding the hold-down mechanism.